Golf is enjoyed by a wide variety of players—players of different genders, and players of dramatically different ages and skill levels. Golf is somewhat unique in the sporting world in that such diverse collections of players can play together in golf outings or events, even in direct competition with one another (e.g., using handicapped scoring, different tee boxes, etc.), and still enjoy the golf outing or competition. These factors, together with increased golf programming on television (e.g., golf tournaments, golf news, golf history, and/or other golf programming) and the rise of well known golf superstars, at least in part, have increased golf's popularity in recent years, both in the United States and across the world.
Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” Manufacturers of all types of golf equipment have responded to these demands, and recent years have seen dramatic changes and improvements in golf equipment. Being the sole instrument that sets a golf ball in motion during play, the golf club also has been the subject of much technological research and advancement in recent years. For example, the market has seen improvements in golf club heads, shafts, and grips in recent years. Additionally, other technological advancements have been made in an effort to better match the various elements of the golf club and characteristics of a golf ball to a particular user's swing features or characteristics (e.g., club fitting technology, ball launch angle measurement technology, etc.).
Despite the various technological improvements, golf remains a difficult game to play at a high level. For a golf ball to reliably fly straight and in the desired direction, a golf club must meet the golf ball square (or substantially square) to the desired target path. Moreover, the golf club must meet the golf ball at or close to a desired location on the club head face (i.e., on or near a “desired” or “optimal” ball contact location) to reliably fly straight, in the desired direction, and for a desired distance. Off-center hits may tend to “twist” the club face when it contacts the ball, thereby sending the ball in the wrong direction, imparting undesired hook or slice spin, and/or robbing the shot of distance. The energy or velocity transferred to the ball by a golf club also may be related, at least in part, to the “coefficient of restitution” (or “COR”) of the club face at the point of contact. The maximum COR for golf club heads is currently limited by the USGA at 0.83. Generally, a club head will have an area of highest response or highest COR relative to other areas of the face, which imparts the greatest energy and velocity to the ball, and this area is typically positioned at the desired ball contact location, usually at the center of the face.
The distance and direction of ball flight can also be significantly affected by the spin imparted to the ball by the impact with the club head. While the ball is in the air, aerodynamic forces caused by the speed and direction of ball spin can cause the trajectory of the ball to be higher or lower, or to curve, and create “pulls,” “pushes,” “draws,” “fades,” “hooks,” “slices,” etc. Additionally, the spin of the ball can change the behavior of the ball as it rolls and bounces after impact with the ground. For example, a high degree of backspin can cause the ball to slow, stop, or even roll backward upon impact, and conversely, topspin or lesser degrees of backspin will cause the ball to travel a greater distance after impact with the ground. Various speeds and directions of spin on the ball can be a product of many factors, including the point of impact, the direction of the club head upon impact, the degree of twisting of the club head upon impact, and the location of the center of gravity of the club head. The interaction between the ball and the club face at the point of impact, including traction, friction, etc., can also have a significant influence on the degree of spin imparted to the ball upon impact.
The cover of a golf ball is typically made of a polymer such as an ionomer or urethane, among other materials. The cover material comes into physical contact with the club face during a golf shot. In order to generate desired backspin or other spin on the ball, a shearing force must be exerted on the ball by the face of the club. Many club heads have grooves on the ball striking face of the club that can aid this interaction by creating areas into which the ball cover can deform during impact, increasing the traction between the ball and the face, to more effectively transmit torque to the ball. The configurations of these grooves, including the widths, depths, shapes, directions, cross-sectional or profile shapes, and distribution of the grooves, among other characteristics, can influence the amount and direction of spin imparted to the ball upon impact. USGA rules may limit the configuration of face grooves, such as by limiting the width, depth, spacing, area, and/or the sharpness (radius) of the edges of the grooves, which can limit the amount of spin that can be imparted to the ball. For example, recent changes to the USGA rules currently require that the “effective radius” of the edges of each groove is not less than 0.010″ and not greater than 0.020″. This is determined by using the “two circles” method as described in the USGA rules, “Determination of Groove Conformance, Impact Area Markings (App II, 5c) Measurement Procedure,” August 2008.
In some circumstances, it may be desirable to impart as little spin as possible to the ball, such as to achieve a straighter and longer ball flight with lower or more boring trajectory and greater rolling distance. For example, many driver-type clubs are designed to impart less spin to the ball upon impact. In other circumstances, it may be desirable to impart a high degree of backspin on the ball, to achieve a higher trajectory and a minimal amount of rolling, or even to draw the ball backward after impacting the ground. For example, many iron-type clubs, hybrid clubs, and fairway wood clubs are designed to impart a greater amount of spin to the ball upon impact. Further, a golfer may wish to have the ability to impart hooking or slicing spin on a ball, such as by altering the form and/or mechanics of the golfer's swing. The grooves in the ball striking face of the golf club head can assist in achieving some or all of these performance characteristics. Accordingly, club head features that can assist in consistently achieving maximum spin on the ball can be advantageous.
The grooves in the face of a golf club head are typically formed in the material of the face through a process such as cutting, machining, forging, molding, etc. Since the face is typically made from a material that has some degree of resilience and flexibility and is not excessively hard, such as a metal, the edges defining the grooves can be susceptible to wear after repeated use. Ground detritus, rocks, sand, gravel, and other hard materials that contact the face in the course of play can become sandwiched between the ball and the face during impact, causing the club face and the grooves in the face to become worn, such as by abrasion, including wearing away of the edges of the grooves, as well as chipping, deformation, gouging the face, or otherwise deteriorating the club face. As the grooves become worn, the ability of the golfer to effectively control the ball flight trajectory and roll of the golf ball, through controlling the amount and axis of spin on the ball, can be compromised. This can be more problematic when the edges of the grooves are less sharp initially, such as due to USGA regulations. However, measuring or detecting wear on the club face and the grooves can be difficult outside of a laboratory or service center. Accordingly, club head features that can facilitate detection of excessive wear on the face and/or the grooves can enable the user to replace the club head before performance is adversely affected. This can be of particular importance to professional golfers, who depend on consistently and reliably producing the desired spin on the ball to achieve their best performance, but can also be useful to amateur and recreational golfers.
Wear on a club head, such as a wood-type club head, can also cause failure of the ball striking face through rupture upon contact with the ball in play. Generally, a club face will become weakened through removal and/or deformation of material on the face prior to rupture. Failure of the face can be troublesome, as replacement of a driver or other wood-type club is not often feasible in the middle of playing a round. As such, failure during a tournament or other competition can be disastrous. Thus, club head features that can facilitate detection of excessive wear on the face enable the user to replace the club head before rupture or other failure occurs.
The present device and method are provided to address the problems discussed above and other problems, and to provide advantages and aspects not provided by prior ball striking devices of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.